1. Technical Field
The present invention relates to an oscillator, an electronic apparatus, and a vehicle.
2. Related Art
A temperature-compensated crystal oscillator (TCXO) has a quartz crystal resonator and an integrated circuit (IC) for oscillating the quartz crystal resonator, wherein the IC compensates (thermally compensates) the deviation (frequency deviation) from the desired frequency (nominal frequency) of the oscillation frequency of the quartz crystal resonator in a predetermined temperature range, and thus, high frequency accuracy can be obtained. Such a temperature-compensated crystal oscillator (TCXO) is disclosed in, for example, JP-A-2006-50529.
Further, the temperature-compensated crystal oscillator is high in frequency stability, and is therefore used for communication equipment and so on for which high performance and high reliability are required.
In general, such an oscillator as described above takes time from when the power is supplied until the frequency becomes stable.
FIG. 24 is a graph showing an example of a cold-start characteristic of a related-art temperature-compensated crystal oscillator. Here, the cold-start characteristic of the oscillator denote temporal characteristic of the output frequency in a period from when the power is supplied (input) to the oscillator to when the action of the oscillator becomes stable. It should be noted that the horizontal axis shown in FIG. 24 represents the elapsed time from when the power supply to the oscillator is started. Further, the vertical axis of the graph shown in FIG. 24 represents the frequency deviation with respect to the frequency at the start-up of the power supply.
In the example shown in FIG. 24, the frequency deviation with respect to the frequency at the start-up of the power supply in the related-art temperature-compensated crystal oscillator is −37 ppb at the time point when 10 seconds have elapsed from the start-up of the power supply, −68 ppb at the time point when 20 seconds have elapsed from the start-up of the power supply, and −72 ppb at the time point when 30 seconds have elapsed from the start-up of the power supply.
However, in the case of using, for example, an oscillator in a communication system, an automated cruise system, or the like, if a period from when the power is supplied to when the frequency becomes stable is long, there is a problem that prompt restoration cannot be achieved in the case in which the system has once been shut down.